1. Field of the Invention
The present invention relates to a zippered bag having a zipper by which a mouth portion to be formed can be opened or closed, and a method for manufacturing such a zippered bag.
2. Description of the Related Art
There have conventionally been known a self-standable pouch or a flat bag with a zipper by which a mouth portion to be formed could be opened or closed. The zipper provided on such a bag is composed of a male track and a female track engageable therewith. The male track and the female track are formed on the inner surfaces of a pair of opposing face members of a main bag body, respectively, so as to face each other and extend in the lateral direction of the main bag body. The zipper substantially extends over the main bag body in the lateral direction so that an opening operation of the zipper causes the main bag body to be opened over the entire region in the lateral direction thereof.
When the bag with the zipper opened is inclined and shaken lightly to hit softly the mouth portion of the bag against the rim of a vessel such as a cup, in order to pour the powdery or granular contents, with which the bag is filled, directly into the vessel, the contents may suddenly be spilled out in an unexpectedly large amount, thus causing inconvenient problems in handling.
In addition, the full length of the zipper is so long to substantially extend over the main bag body in the lateral direction, thus increasing the probability of occurrence of clogging of the female track with the contents. Especially in case where the bag is filed with the fine granular contents, the probability of occurrence of clogging may remarkably increase. The occurrence of clogging of the female track with the contents may make it impossible to keep the zipper in a completely closed state, thus deteriorating a function of maintaining quality of the contents in an appropriate manner.
An object of the present invention, which was made in order to solve the above-described problems, is therefore to provide a zippered bag, which has an excellent handling property facilitating a pouring operation of the bag, and prevents occurrence of clogging of the zipper, as well as a method for manufacturing such a zippered bag.
In order to attain the aforementioned object, a zippered bag of the first aspect of the present invention comprises:
a main bag body having first and second opposing face members, a top, a bottom, and first and second opposing sides; and
a zipper disposed on said main bag body,
wherein:
said zipper extends from one of said top and said bottom to one of said first and second opposing sides so as to be oblique relative to said one of said top and said bottom.
According to the above-mentioned features of the first aspect of the present invention, it is possible to form a mouth portion at a corner of the main bag body, thus decreasing the size of the mouth portion. As a result, there can be provided the zippered bag, which permits to facilitate the pouring operation of the bag filled with the powdery or granular contents, without suddenly spilling the contents.
In addition, decrease in size of the mouth portion leads to decrease in length of the zipper. It is therefore possible to reduce the probability of occurrence of clogging of the zipper, even when the bag is filled with fine powdery or granular material. Even if the clogging of the female track occurs, the material with which the zipper is clogged can easily be removed therefrom.
In the second aspect of the present invention, said zipper may comprise a male track and a female track engageable therewith. According to the feature of the second aspect of the present invention, the structure of the zipper becomes simple and reliable functions thereof can be ensured.
In the third aspect of the present invention, said male track and said female track may be formed on inner surfaces of said first and second opposing face members by an injection molding, respectively. According to the above-mentioned feature of the third aspect of the present invention, formation of the male track and the female track can be facilitated.
In the fourth aspect of the present invention, each of said male track and said female track may comprise a main portion and end portions provided on opposite ends of said main portion in a longitudinal direction thereof, each of said end portions having a smaller height than that of said main portion. According to the above-mentioned feature of the fourth aspect of the present invention, it is possible to reduce the probability that a gap may be formed between heat-sealed portions of the main body and the longitudinal edge of the zipper.
In the fifth aspect of the present invention, said main bag body may have a sealed zone, which is placed on an outer side of said zipper, said sealed zone having opening guide portions, which are provided in parallel with said zipper so that said sealed zone is to be easily torn open along said opening guide portions. According to the above-mentioned feature of the fifth aspect of the present invention, the sealed zone can easily be torn open along the opening guide portions and the mouth portion completely formed in the bag along the straight line can be obtained. In addition, the opening guide portions may serve as a reinforcement member for the mouth portion of the bag.
In order to attain the aforementioned object, a method of the sixth aspect of the present invention for manufacturing a zippered bag comprises the steps of:
folding a sheet of film to provide first and second opposing face members, said first and second opposing face members having a folded bottom edge, first and second opposing side edges and opposing top edges;
folding upper portions of said first and second opposing face members outward along reference lines, which respectively extend on said first and second opposing face members in parallel with said opposing top edges so as to be apart therefrom by a prescribed distance, to provide first and second folded portions with their inner surfaces exposed;
heat-sealing said first and second opposing side edges together except said first and second folded portions;
subjecting said first and second folded portions to an injection molding to form a male track on the inner surface exposed of one of said first and second folded portions and a female track on the inner surface exposed of an other of said first and second folded portions, said male track and said female track being placed along straight lines, which extend from respective side edges of said first and second folded portions to respective top edges thereof, said male track and said female track being engageable with each other to constitute a zipper;
unfolding said first and second folded portions to bring the opposing side edges of the one of said first and second folded portions into contact with the opposing side edges of the other thereof to convert said first and second folded portions into first and second unfolded portions and engage said male track with said female track to keeping said zipper in a closed state so as to be oblique relative to said opposing top edges, thus providing upper and lower engaging points of the zipper;
heat-sealing the opposing side edges of one of said first and second unfolded portions to the opposing side edges of an other thereof, respectively, to form a first upper-side heat-sealed portion including said lower engaging point and a second upper-side heat-sealed portion; and
heat-sealing the top edges of said first and second unfolded portions together in a region from said upper engaging point to an upper end of said first upper-side heat-sealed portion, thus forming a non-sealed opening portion in a region from said upper engaging point to un upper end of said second upper-side heat-sealed portion.
According to the above-mentioned features of the sixth aspect of the present invention, it is possible to form a mouth portion at a corner of the main bag body, thus decreasing the size of the mouth portion. As a result, there can be provided the zippered bag, which permits to facilitate the pouring operation of the bag filled with the powdery or granular contents, without suddenly spilling the contents. In addition, decrease in size of the mouth portion leads to decrease in length of the zipper. It is therefore possible to reduce the probability of occurrence of clogging of the zipper, even when the bag is filled with fine powdery or granular material. Even if the clogging of the female track occurs, the material with which the zipper is clogged can easily be removed therefrom. Application of the injection molding facilitates formation of the zipper, which extends from the top of the main bag body to the side thereof so as to be oblique relative to the top of the main bag body. The zippered bag as manufactured has the non-sealed portion at the top of the bag, thus making it possible to fill the bag with the contents through the non-sealed portion.
In order to attain the aforementioned object, a method of the seventh aspect of the present invention for manufacturing a zippered bag comprises the steps of:
continuously providing an elongated linear zipper on an inner surface of a strip of film, while traveling said strip of film in a longitudinal direction thereof, to prepare a film-material strip with the elongated linear zipper;
determining areas, each of which has a top, a bottom and opposing sides, of the film-material strip to which a heat-sealing step is to be applied, so that said elongated linear zipper extends from said top to one of said opposing sides so as to be oblique relative to said top;
subjecting said areas of the film-material strip to said heat-sealing step; and
cutting said film-material strip into a plurality of zippered bags.
According to the above-mentioned features of the seventh aspect of the present invention, it is possible to manufacture the zippered bag utilizing the linear zipper, which has previously been formed through an extrusion molding, even with the use of the other molding method than the injection molding. As a result, it is not necessary to provide a manufacturing line for the zippered bag with the injection molding machine, thus making it possible to simplify the manufacturing process.